Show HN: Koda Validate – Typesafe, combinable validation for Python

https://github.com/keithasaurus/koda-validate

by keithasaurus • 4 years ago

30 9 4 years ago

How does this compare with say Pydantic?

This seems more lower level, and provides building blocks with combinators which seems like a Validation / Applicative approach.

I'm probably just going to use pydantic though.

keithasaurus4• 4 years ago

There are a few differences:

- it is typesafe without any plugins or type-hint hacks

- exceptions are not raised as part of validation

- there is a consistent, type-enforced notion of what a validator is

- it's explicit, no implicit type coercions

- it's meant to be easier to build complex validators by combining validators

- validators are meant to be easily inspectable, meaning you can create things like API schemas from them

- errors are json/yaml serializable, so if needed they can be passed over the wire directly (or modified, if desired)

carapace• 4 years ago

I like it.

One thing that occurs to me: I don't want to have to describe my data in two places. Like how in the first example the dataclass Person has all the information needed to define the person_validator.

pugio• 4 years ago

It's worth noting that the Pydantic author stated he's rewriting parts of the validation in Rust for the next major release, with the aims of drastically improving performance.

I'm definitely interested in a simple type-safe validator library, but that planned performance boost is pretty tempting.

keithasaurus4• 4 years ago

That's really helpful to hear. A few thoughts:

- I haven't benchmarked this against pydantic... I guess I should!

- I would _hope_ that Koda Validate is at least competitive with Pydantic... because Koda Validate's main core improvement (IMO) is a consistent idea of what a validator is, validators in Koda Validate are actually much simpler than in Pydantic, meaning I would generally expect fewer instructions to be executed

- 3.11 (and 3.12) are both focused on performance. Both pydantic and Koda Validate might get some "free" performance boosts anyway (Thanks CPython devs!)

keithasaurus4• 4 years ago

Quick follow-up that it looks like koda_validate is usually slower when validating dictionaries out of the box. Good news is it's clear where I should optimize, and that I'll add some benchmarks to this; optimistic Koda Validate can get faster than Pydantic. Thanks for the feedback!

Show HN: Koda Validate – Typesafe, combinable validation for Python

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